What are the Health Risks?

Chromium can exist in a number of different valence states. Yet OSHA has determined that Hexavalent Chromium, Cr (VI)presents the greatest health risk.  The most significant health risks result from exposure to Hexavalent Chromium particles by inhalation and through skin contact.

Particles
Particles of hexavalent chromium can be in mists, dust or fumes.  Mists can come from using molten metal such as chrome plating baths or painting.  Dusts can come from grinding or cutting.  Fumes can be generated during torch cutting and welding operations.

Inhalation
Hexavalent chromium particles are inhaled through the mouth and nose.  Large particles may be trapped in the mucous membranes of the mouth and nose. 

Smaller particles may travel farther and deposit in the throat, trachea or the left and right bronchi.  These particles are likely to be coughed up and swallowed.

The smallest particles will travel beyond the bronchi and deposit in the alveoli.  These are small, thin air sacs that are arranged in clusters like bunches of balloons.  Tiny blood vessels surround each of the 300 million alveoli.  Oxygen moves across the walls of the air sacs and is picked up by the blood and carried to the rest of the body.

The health risks from hexavalent chromium particles that deposit in the alveoli will depend on the particle's solubility.  The particles can be highly soluble, slightly soluble or insoluble.

Highly Soluble
Highly soluble hexavalent chromium particles will quickly dissolve and easily pass through the alveoli and into the bloodstream.  Once there the particles are absorbed by the red blood cells, or erythrocytes, where they are reduced to trivalent chromium.

Insoluble
Insoluble hexavalent chromium particles will stay in the alveoli.  They will eventually be absorbed by lung white blood cells, specifically phagocytes, and slowly reduced to less harmful trivalent chromium.

Slightly Soluble
Slightly soluble hexavalent chromium particles will slowly pass through the alveoli and absorbed into erythrocytes where they are reduced to trivalent chromium.

Lung Cancer
Exposure to slightly soluble hexavalent chromium particles has produced a higher incidence of respiratory tract tumors than has exposure to highly soluble or insoluble particles.  This reflects the probability that lung tissue is exposed to a consistent high local concentration of hexavalent chromium while the particles are slowly dissolving.

Highly soluble and insoluble particles do not appear to provide the same level of exposure.  However these particles still present a risk for lung tumors.

Non-Cancerous Respirator Effects
Inhalation exposure to soluble hexavalent chromium can lead to nasal irritation, nasal ulcerations and perforations, asthma and bronchitis.

Other Problems
Direct skin contact with hexavalent chromium can lead to dermatitis and skin ulceration.  Direct eye contact may lead to conjunctivitis.